Environment Canada is warning of extreme cold and possible snow squalls for parts of southwestern Ontario.
An extreme cold warning has been issued for Huron, Perth, Grey, Bruce and Wellington counties.
Forecasters say a period of very cold wind chills is expected as a strong front crosses through southern Ontario Thursday morning.
Colder temperatures and gusting north winds are expected to bring wind chills near -30 C on Thursday afternoon into Friday morning.
Environment Canada says the warning will likely be expanded as the cold air advances on Thursday.
Meanwhile, a snow squall watch was issued Wednesday afternoon for London-Middlesex, eastern Lambton County, Huron County and southern Bruce County.
Snow squalls are expected to develop overnight with bands that could significantly reduce visibility due to heavy and blowing snow.
Squalls are expected to be most intense along the Saugeen Shores and near Wingham on Wednesday night.
Thursday morning, forecasters say snow squalls will move onshore near Goderich and Grand Bend and possibly into eastern Lambton County, then reaching as far as London by Thursday afternoon or night.
Environment Canada is reminding drivers that squalls mean weather can vary a lot within just a few kilometres and visibility can be suddenly reduced.
For up-to-date watches and warnings visit the Environment Canada website.
